Entrance structure for a liquid conduit

ABSTRACT

An entrance structure for a storm sewer pipe is designed so that the storm sewer pipe has full flow therethrough when the height of the water at the inlet of the entrance structure is equal to or greater than the height of the inlet of the storm sewer pipe.

United States Patent [1 1 Gray [ Dec. 11, 1973 ENTRANCE STRUCTURE FOR ALIQUID CONDUIT Inventor: Ira M. Gray, Route 2, Stamping Ground, Ky.40379 Filed: July 24, 1972 Appl. No.: 274,575

[1.8. CI. 138/109, 61/16 Int. Cl. F161 9/00 Field of Search 138/109,100, 102,

References Cited UNITED STATES PATENTS Fischer 61/16 D205,678 9/1966Williams D44/29 K Primary ExaminerGeorge E. Lowrance AssistantExaminerSteven M. Pollard Attorney-Frank C. Leach, Jr.

[57] ABSTRACT An entrance structure for a storm sewer pipe is designedso that the storm sewer pipe has full flow therethrough when the heightof the water at the inlet of the entrance structure is equal to orgreater than the height of the inlet of the storm sewer pipe.

10 Claims, 9 Drawing Figures PAIENIEDMI H913 78s m1 1 nr 2 FIG.1

FIG. 2

PAIfNIEII I I975 SIIEIZNZ FIG. 3

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FIG. 4

FIG. 5

" FIG.9

FIG. 6

ENTRANCE STRUCTURE FOR A LIQUID CONDUIT In the flow of liquid through aconduit such as a storm sewer pipe, for example, a critical problem hasbeen to utilize the entire area of the passage extending through thestorm sewer pipe for flow of water. When the height of the water becomesequal to or greater than the height of the storm sewer pipe at itsentrance, it would seem that the passage in the storm sewer pipe wouldbe completely filled. However, this does not occur for moderate to steepslopes and a portion (approximately one-third) of the passage of thestorm sewer pipe does not carry water.

One is required to utilize a storm sewer pipe having an area capable ofcarrying a specific quantity of water. Because of the inability of thestorm sewer pipe to have its passage completely filled, it has beennecessary to use a storm sewer pipe of a larger area than it would berequired if the passage of the storm sewer pipe were capable of beingcompetely filled with water.

Various means for increasing the flow of liquid through a conduit havepreviously been suggested. For example, tapered inlets have beenproposed. While these enable the conduit to carry more water than if astandard headwall is employed with the storm sewer pipe, there is stilla significant portion of the passage not filled when the level of wateris higher than the height of the storm sewer pipe at its entrance.

The use of a plate or hood extending forwardly of the entrance of thestorm sewer pipe and at the top of the storm sewer pipe also has beenproposed. However, supports for the plate catch trash and the like. Thistrash can eventually partially block the entrance to significantlyreduce the flow of water through the storm sewer pipe. While the plateis not capable of enabling the storm sewer pipe to be completely filled,it is significant improvement over a storm sewer pipe having only astandard headwall.-

The inability to utilize the full area of the passage in the storm sewerpipe is deemed to be caused by a vortex, which is formed at the entranceto the storm sewer pipe by the standard headwall, for example. Thepreviously mentioned plate, for example, reduces the formation of thevortex.

The present invention satisfactorily overcomes the foregoing problems byreplacing the headwall with an entrance structure in which the vortex isprevented from forming. It is believed that the entrance structure ofthe present invention prevents the vortex from forming since there is noabrupt change in the path of a water particle from the top of thesurface to the top of the storm sewer pipe. That is, the entrancestructure uses a streamlined flow arrangement so that there is no areaof low pressure as is produced by the abrupt angle at the face of thestandard headwall.

Accordingly, the introduction of any air into the entrance of the stormsewer pipe which uses the entrance structure of the present inventiondoes not cause collapse of the water within the pipe as occurs when avortex is present. Therefore, the entrance structure of the presentinvention enables the storm sewer pipe to have its passage completelyfilled when the level of the water is higher than the height of theentrance of the storm sewer pipe.

An object of this invention is to provide an entrance structure for aliquid conduit to cause full flow through the liquid conduit when theheight of the liquid at the entrance of the conduit is equal to orgreater than the height of the inlet of the conduit.

- Another object of this invention is to provide an easily constructedentrance structure for a liquid conduit.

Other objects of this invention will be readily perceived from thefollowing description, claims, and drawings.

This invention relates to an entrance structure for a liquid conduithaving a passage of circular cross section. The entrance structureincludes a hollow member secured to the liquid conduit and having apassage extending with its outlet having the same area and configurationas the inlet of the liquid conduit passage. The hollow member passagehas its inlet of a greater area than its outlet with the area of thepassage decreasing substantially progressively from its inlet to itsoutlet. The hollow member passage has at least the upper half of itsperiphery formed by a circular arc with its center being axially alignedwith the center of the liquid conduit passage.

The attached drawings illustrate a preferred embodiment of theinvention, in which:

FIG. 1 is a side sectional view of a storm sewer pipe having theentrance structure of the present invention;

FIG. 2 is a schematic view showing the relationship of the passage inthe entrance structure and its cooperation with the storm sewer pipe;and

FIGS. 3-9 are schematic end views of portions of the passage of theentrance structure of the present invention and taken along lines 3-3.to 9-9, respectively, of FIG. 2.

Referring to the drawings and particularly FIG. 1, there is shown acylindrical conduit 10 such as a storm sewer pipe, for example, having acircular cross section and disposed beneath an earth fill 11. Theconduit 10 has a passage 12 extending therethrough of circular crosssection with a diameter D.

An entrance structure 14 is secured to the conduit 10 and has a passage15 extending therethrough with its outlet 16 (see FIGS. 2 and 3) havingthe same area as the area of the passage 12 in the conduit 10. Theoutlet 16 is circular and has the diameter D. the passage 15 of theentrance structure 14 has its inlet 17 of greater area than the area ofthe outlet 16 of the passage 15 with the area of the passage 15increasing substantially progressively from its outlet 16 to its inlet17.

The entrance structure 14 is formed of concrete and secured to theconduit 10 by a mold, which has the desired shape to give the desiredconfiguration to the passage 15. The mold may be formed of any suitablematerial such as fiberglass, for example, in forming the entrancestructure 14.

In order to obtain the most efficient flow through the passage 15 of theentrance structure 14, it is necessary for various segments of thepassage 15 to have specific relationships to each other. However, theserelationships can be varied within certain limits and still obtainefficient flow through the conduit 10 although the conduit 10 would notbe completely filled. For example, if the length of the passage 15 inthe entrance structure 14 is reduced 10% from its preferred length, theflow efficiency becomes approximately 97 percent rather than 100percent. If the length of the passage 15 of the entrance structure 14 isreduced 50% from its preferred length, then the efficiency will beapproximately percent. With this reduction, the entrance structure 14 isonly slightly more effective than a standard headwall, for example, sothat the entrance structure 14 would cease to be of value.

The preferred length of the passage 15 of the entrance structure 14 isequal to the diameter of the passage 12 in the conduit 10. Thus, thepreferred length of the passage 15 is D.

The periphery of the passage 15 is circular at its outlet 16 (see FIG.3) while its inlet 17 (see FIG. 9) has a first circular arc portion 18and a non-circular or flat portion 19 with a pair of second circular arcportions 20, which have the same radius but a smaller radius than theradius of the circular arc portion 18, extending between each end of thecircular arc portion 18, which is semicircular, and each end of the flatportion 19. Between the outlet 16 and the inlet 17, the periphery of thepassage 15 changes in a smooth streamline.

The periphery of the passage 15 is still circular at section 21 (seeFIG. 4) and at section 22 (see FIG. 5). The periphery of the passage hasa small flat or noncircular portion 23 at its section 24 (see FIG. 6)while the remainder of the periphery of the passage 15 at its section 24is a first circular arc portion 25, which is a semi-circle, and a pairof second circular arc portions 26, which are the same radius but asmaller radius than the radius of the first circular arc portion 25,connecting each end of the first circular arc portion 25 to one of theends of the flat portion 23.

At its section 27 (see FIG. 7), the periphery of the passage 15 isformed by a non-circular or flat portion 28, a first circular arcportion 29, and a pair of second circular arc portions 30. As seen fromFIGS. 6 and 7, the non-circular portion 28 of the section 27 is widerthan the non-circular portion 23 of the section 24.

The second circular arc portions 30 have the same radius, which issmaller than the radius of the first circular arc portion 29. Each ofthe second circular arc portions 30 connects one end of the firstcircular arc portion 29, which is a semi-circle, to one end of the flatportion 28.

At its section 31 (see FIG. 8), the periphery of the passage 15 has anon-circular or flat portion 32, a first circular arc portion 33, and apair of second circular arc portions 34.

The second circular arc portions 34 of the section 31 have the sameradius, which is smaller than the radius of the first circular arcportion 33. Each of the second circular arc portions 34 connects one endof the first circular arc portion 33, which is a semi-circle, to one endof the flat portion 32. The non-circular portion 32 is wider than thenon-circular portion 28 but smaller than the non-circular portion 19.Thus, the flat portion of the passage 15 progressively decreases fromits inlet With the length of the passage 15 being equal to the diameterD of the passage 12 of the conduit 10, the section 21 is disposed adistance D/6 from the outlet 16 of the passage 15 as measured along alongitudinal axis passing through the center of the passage 12 of theconduit 10. The section 22 is disposed at distance of D/4 from thesection 21 and a distance of DM from the section 24.

The section 27 is disposed a distance of D/6 from the section 24 and adistance of D/ 12 from the section 31. The inlet 17 of the passage 15 isat a distance of D/l2 from the section 31 of the passage 15.

Between the outlet 16, which as a radius of 0.5D, and the section 21,which has a radius of 0.5092D, the periphery of the passage 15 increasesalong a curve 35 (see FIG. 2). The curve 35 is generated by a radius ofcurvature of LSD.

Between the section 21 and the section 22, the periphery of the passage15 increases along a straight line 36. The section 22 has a radius of0.53695D.

The first circular arc portion 25 (see FIG. 6) of the section 24 isformed with a radius of 0.5865 lD while each of the second circular'arcportions 26' has a radius of 0.57407D. so that the non-circular or flatportion 23 of the section 24 is located a distance of 0.57407D from alongitudinal axis passing through the center of the passage 12 of theconduit 10.Between the first circular arc portion 25 and the secondcircular arc portions 26 of the section 24 and the same correspondingportion of the section 22, a curve 37 (see FIG. 2) extends and has aradius of curvature of LSD. The flat portion 23 of the section 24 taperstoward the section 22 and terminates prior to the section 22.

The first circular arc portion 29 (see FIG. 7) of the section 27 isformed with a radius of 0.65113D while each of the second circular arcportions 30 has a radius of 0.59259D so that the flat portion 28 of thesection 27 is located a distance of 0.59259D from a longitudinal axispassing through the center of the passage 12 of the conduit 10. A curve39 (see FIG 2) extends between the first circular arc portion 29 of thesection 27 and the corresponding first circular arc portion 25 of thesection 24 and between the second circular arc portions 30 of thesection 27 and the corresponding second circular arc portions 26 of thesection 24 and has a radius of curvature of D. The fiat portion 32 (seeFIG. 8) of the section 32 extends to the flat portion 28 (see FIG. 7) ofthe section 27 in a reducing relation.

The section 31 has the first circular arc portion 33 formed with aradius of 0.739D while each of the second circular arc portions 34 has aradius of 0.60185D so that the flat portion 132 is located at a distanceof 0.60185D from a longitudinal axis passing through the center of thepassage 12 of the conduit 10. A curve 40 (see FIG. 2) extends betweenthe first circular arc portion 29 of the section 27 and the firstcircular arc portion 33 of the section 31 and between the secondcircular arc portions 30 of the section 27 and the second circular arcportions 34 of the section 31. The curve 40 has a radius of curvature ofD/2. The flat portion 32 of the section 31 extends toward the flatportion 28 of the section 27 in a reducing relation.

The inlet 17 of the passage 15 has the first circular arc portion 18(see FIG. 9) formed with a radius of 0.84l26D while each of the secondcircular arc portions 20 has a radius of 0.61 l 1 1D so that the fiatportion 19 is disposed 0.61 l 1 ID from a longitudinal axis passingthrough the center of the passage 12 of the conduit 10. A curve 41 (seeFIG. 2) extends between the first circular arc portion 33 of the section31 and the first circular arc portion 18 of the inlet 17 and between thesecond circular arc portions 34 of the section 31 and the secondcircular arc portions 20 of the inlet 17. The curve 41 has a radius ofcurvature of 2 D/9. The flat portion 19 of the inlet 17 extends towardthe flat portion 32 of the section 31 in a reducing relation.

Accordingly, the periphery of the passage 15 of the entrance structure14 is circular from its outlet 16 for 5/12 of the length of the passage15 with an increasing radius. Then, the remainder of the length of thepassage 15 to its inlet 17 is formed with an increasing flat ornon-circular portion along the bottom of the periphery with theremainder of the periphery being circular with are portions of twodifferent radii at each section and the radii increasing at eachsection.

The non-circular or flat portion of the periphery of the passage 15 isemployed to reduce the amount of water that would stand at the inlet 17to the passage 15 if the inlet 17 were circular. Furthermore, it is notnecessary for the portion of the periphery of the passage 15 to be flatas other non-circular portions such as a portion of an ellipse, forexample, could be employed, if desired. lt should be understood that aslight amount of water will still stand at the inlet 17 of the passage15 but it is significantly reduced through using the noncircular portionat the bottom of the passage 15.

While the passage 15 of the entrance structure 14 has been shown anddescribed as having a specific relationship between each of the varioussections of the passage 15, it should be understood that the specificdimensions are not necessary. for satisfactory operation of the entrancestructure 14. That is, it is only necessary that the area of the passage15 decrease substantially progressively from the inlet 17 to the outlet16. The particular radii of curvatures and straight lines and thespecific distances therebetween give the most desired result. However,the passage 15 will function to maintain the conduit substantiallyfilled with slight deviations from the specific dimensionalrelationships.

It should be understood that each of the circular sections 21 and 22 ofthe periphery of the passage and the circular outlet 16 of the passage15 has its center on a longitudinal axis passing through the center ofthe passage 12 of the conduit 10 so that its center is axially alignedwith the center of the passage 12 of the conduit 10. Likewise, the firstcircular arc portion of each of the sections 24, 27, and 31 of theperiphery of the passage 15 and of the inlet 17 of the passage 15 hasits center on the longitudinal axis passing through the center of thepassage 12 of the conduit 10 so that its center is axially aligned withthe center of the passage 12 of the conduit 10.

It also should be understood that the center for each of the secondcircular arc portions of each of the sections 24, 27, and 31 of theperiphery of the passage 15 and the inlet 17 of the passage 15 is at theintersection of a line extending from the end of the second circular arcportion adjacent the end of the first circular arc portion toward thecenter of the first circular arc portion and a line extending from theend of the second circular arc portion adjacent the flat portion andperpendicular to the flat portion. Thus, the center of each of thesecond circular arc portions is located at the perpendicular junction ofits two outside radii.

An advantage of this invention is that it reduces the cost for a stormsewer since smaller diameter pipes can carry the same quantity ofliquid. Another advantage of this invention is that it enables a stormsewer pipe to carry a larger quantity of liquid.

For purposes of exemplification, a particular embodiment of theinvention has been shown and described according to the best presentunderstanding thereof. However, it will be apparent that changes andmodifications in the arrangement and construction of the parts thereofmay be resorted to without departing from the spirit and scope of theinvention.

1 claim:

1. An entrance structure for a liquid conduit having a passage ofcircular cross section, said entrance structure including a hollowmember secured to the liquid conduit and having a passage extendingtherethrough, said hollow member passage having its outlet in a planesubstantially perpendicular to the longitudinal axis of the liquidconduit passage and its inlet in a plane substantially parallel to theplane containing its outlet, said hollow member passaging having itsoutlet with a greater area than its outlet, said hollow member passagehaving its cross sectional area decrease substantially progressively ina non-linear relation from its inlet to its outlet, said hollow memberpassage having at least the upper half of its periphery formed by acircular arc with its center being axially aligned with the longitudinalaxis of the liquid conduit passage, the periphcry of said hollow memberpassage having a noncircular portion adjacent its bottom from its inlettoward its outlet for a distance greater than one half of the length ofsaid hollow member passage, the periphery for the remainder of thelength of said hollow member passage being circular and extending fromits oulet toward its inlet for a distance greater than one-third of thelength of said hollow member passage, and the noncircular portion of theperiphery of said hollow member passage being smaller than the diameterof the liquid conduit passage.

2. The entrance structure according to claim 1 in which th circularportion of the periphery of said hollow member passage extends from itsoutlet toward its inlet for 5/12 of the length of said hollow memberpas-- sage.

3. The entrance structure according to claim 2 in which the non-circularportion of the periphery of said hollow member passage progressivelydecreases from the inlet of said hollow member passage.

4. The entrance structure according to claim 3 in which said hollowmember passage has a length equal to the diameter of the liquid conduitpassage.

5. The entrance structure according to claim 1 in which said hollowmember passage has a length equal to the diameter of the liquid conduitpassage.

6. The entrance structure according to claim 1 in which said hollowmember passage has a length no greater than the diameter of the liquidconduit passage.

7. The entrance structure according to claim 1 in which any portion ofthe length of the periphery of said hollow member passage having thenon-circular portion includes a first arc of a first radius and forminga semicircle, a second arc of a second radius beginning at one end ofthe first arc, a third arc of the second radius beginning at the otherend of the first arc, the noncircular portion connecting the other endsof the second and third circular arcs to each other, and the firstradius being larger than the second radius.

8. The entrance structure according to claim 7 in which the non-circularportion connecting the ends of the second and third are is a flatportion.

9. The entrance structure according to claim 4 in which any portion ofthe length of the periphery of said hollow member passage having thenon-circular portion includes a first arc of a first radius and forminga semicircle, a second arc of a second radius beginning at one end ofthe first are, a third are of the second radius beginning at the otherend of the first arc, the noncircular portion connecting the other endsof the second and third circular arcs to each other, and the firstradius being larger than the second radius.

10. The entrance structure according to claim 9 in which thenon-circular portion connecting the ends of the second and third are isa flat portion.

* i i i

1. An entrance structure for a liquid conduit having a passage ofcircular cross section, said entrance structure including a hollowmember secured to the liquid conduit and having a passage extendingtherethrough, said hollow member passage having its outlet in a planesubstantially perpendicular to the longitudinal axis of the liquidconduit passage and its inlet in a plane substantially parallel to theplane containing its outlet, said hollow member passaging having itsoutlet with a greater area than its outlet, said hollow member passagehaving its cross sectional area decrease substantially progressively ina nonlinear relation from its inlet to its outlet, said hollow memberpassage having at least the upper half of its periphery formed by acircular arc with its center being axially aligned with the longitudinalaxis of the liquid conduit passage, the periphery of said hollow memberpassage having a non-circular portion adjacent its bottom from its inlettoward its outlet for a distance greater than one half of the length ofsaid hollow member passage, the periphery for the remainder of thelength of said hollow member passage being circular and extending fromits oulet toward its inlet for a distance greater than one-third of thelength of said hollow member passage, and the non-circular portion ofthe periphery of said hollow member passage being smaller than thediameter of the liquid conduit passage.
 2. The entrance structureaccording to claim 1 in which th circular portion of the periphery ofsaid hollow member passage extends from its outlet toward its inlet for5/12 of the length of said hollow member passage.
 3. The entrancestructurE according to claim 2 in which the non-circular portion of theperiphery of said hollow member passage progressively decreases from theinlet of said hollow member passage.
 4. The entrance structure accordingto claim 3 in which said hollow member passage has a length equal to thediameter of the liquid conduit passage.
 5. The entrance structureaccording to claim 1 in which said hollow member passage has a lengthequal to the diameter of the liquid conduit passage.
 6. The entrancestructure according to claim 1 in which said hollow member passage has alength no greater than the diameter of the liquid conduit passage. 7.The entrance structure according to claim 1 in which any portion of thelength of the periphery of said hollow member passage having thenon-circular portion includes a first arc of a first radius and forminga semicircle, a second arc of a second radius beginning at one end ofthe first arc, a third arc of the second radius beginning at the otherend of the first arc, the non-circular portion connecting the other endsof the second and third circular arcs to each other, and the firstradius being larger than the second radius.
 8. The entrance structureaccording to claim 7 in which the non-circular portion connecting theends of the second and third arc is a flat portion.
 9. The entrancestructure according to claim 4 in which any portion of the length of theperiphery of said hollow member passage having the non-circular portionincludes a first arc of a first radius and forming a semicircle, asecond arc of a second radius beginning at one end of the first arc, athird arc of the second radius beginning at the other end of the firstarc, the non-circular portion connecting the other ends of the secondand third circular arcs to each other, and the first radius being largerthan the second radius.
 10. The entrance structure according to claim 9in which the non-circular portion connecting the ends of the second andthird arc is a flat portion.